Originally Posted by DaveSSS

SRAM RDs need uniform lever pulls and a Campy shifter produces nonuniform pulls, so the results won't be perfect by any means. Thre are also two version of 9 speed shifters. The earlier models pulled and average of 3.2mm per shift, while the newer ones pull an average of 3mm. I've never measured the pulls on a 9 speed shifter personally, but I have done so with 10 speed. While the average pull is about 2.8mm, the actual pulls are 2.5mm five times, 3mm twice and 3.5mm twice.

The significantly smaller pulls on the first five shifts are the problem. There will be lots of lag at the RD after those first five shifts.